| The mechanical behavior of solder joints used in the computer industry has been studied from three different points of view. First, a three-dimensional linear elastic model has been implemented to illustrate the structural problem involved with the geometry of the solder joints. Then, the material of the alloy (96.5%Pb - 3.5%Sn) has been characterized within the framework of two nonlinear models: first, a constitutive equation has been derived through the endochronic theory which has been extended to include stress relaxation as well as failure. Finally, a more sophisticated constitutive equation has been developed by considering the micro-mechanisms involved during the solder deformation. This latter gives more physical interpretations of the material behavior and also predicts failure in a fairly good agreement with the experimental tests. |
